Along with the development of concentrating photovoltaic technology (CPV) in recent years, solar cells of GaAs and related III-V group compounds have been attracting increasingly more attention due to their high photoelectric conversion efficiency. InGaP/GaAs/Ge triple-junction solar cells are widely adopted III-V group compound semiconductor multi junction solar cells. In these solar cells, the lattice constants of all subcells are substantially matched with each other. The widths of band gaps from top down are approximately 1.86 eV for InGaP, approximately 1.42 eV for GaAs, and approximately 0.78 eV for Ge, thus realizing an effective utilization of solar spectrum via a conversion efficiency (AM1.5) as high as 32% (as per American Spectrum Lab) and 41.6% under concentrated conditions. With band gap matching design, the conversion efficiency of the GaInP/GaAs/InGaAs inverted multi junction solar cell is up to 32% under AMO and 1sun conditions and even more than 40% under high concentrated conditions (500×, AM1.5). In the photovoltaic industry, the substrate cost generally takes up 30-50% of the total solar cell cost and becomes one of the main factors for high prices of solar cells.